问题:

In my iOS app I'm trying to perform following simple animation:

- (void)dismissToolbar {       NSLog(@"bx: %f by: %f bw: %f bh: %f ",             toolbar.frame.origin.x,             toolbar.frame.origin.y,             toolbar.frame.size.width,             toolbar.frame.size.height);      CGRect tempRect = CGRectMake(0,                                  toolbar.frame.origin.y + toolbar.frame.size.height,                                  toolbar.frame.size.width,                                  toolbar.frame.size.height);      [UIView animateWithDuration:animationsDuration                           delay:0                         options:UIViewAnimationOptionBeginFromCurrentState | UIViewAnimationOptionAllowAnimatedContent                      animations:^{                          NSLog(@"bx: %f by: %f bw: %f bh: %f ",                                tempRect.origin.x,                                tempRect.origin.y,                                tempRect.size.width,                                tempRect.size.height);                          toolbar.frame = tempRect;   // frame value doesn't change here!                      }                      completion:^(BOOL finished) {                           NSLog(@"bx: %f by: %f bw: %f bh: %f ",                                toolbar.frame.origin.x,                                toolbar.frame.origin.y,                                toolbar.frame.size.width,                                toolbar.frame.size.height);                          NSLog(@"dismiss toolbar complete");                          [toolbar setHidden:YES];                          isPlayerToolbarActive = NO;                          isDissmissingToolbar = NO;                      }      ];      [[NSNotificationCenter defaultCenter] postNotificationName:@"animateSidePanels" object:@"removingPlayerToolbar"]; }